Suspension means for acoustical absorbers



March 28, 1950 G; BEERS SUSPENSION MEANS FOR ACOUSTICAL ABSORBERS FiledDec. 27, 1945 x Fly] ///////////////////////////1 V////////////// flnnentor 'earye L Been* (Ittorneg Patented Mar. 28, 1950 UNITED STATESPATENT' OFFICE SUSPENSION MEANS FOR ACOUSTICAL ABSORBERS George L.Beers, Haddonfield, N. J., assignorto Radio Corporation of America, acorporation of Delaware ApplicaticnDccenher 27, 1943, Serial No.515,'763

volume of air and the wall structure of which is constituted by amaterial which is perviousto sound waves 'but which offers a highdissip'ative 'impeclance thereto` By making the wallstructure of such amaterial and making thecavity or space within the casing so largethat'the Volume of air therein offers a very small impedance to thesound waves, a very highly efcient clifir'action type absorber isprovided. i

As disclosed by Olsen in his aforesaid application, the absorbing unitor "acoustic sink," as he has called it, may be made up from a suitablyblanked sheet which can be folded to provide a box-like structure.However, units so constructed require a series of clcling, assemblingand mounting Operations at the point of use which are time c'o nsumingand relatively costly. i To avoid 'these objectio-ns, it has beenproposecl heretofore to form the absorber units or sinks of a pair ofcomplemental parts which may be nested together compactly for storage,but which can be assembled when the unit is to be set up for usebyplacing the two'halves together and securing them to each other by anadhesive, adhesive tape, stapling, or the like. The assembled unitsarethen ready for installation on `suitable supporting membersthroughout e, room, auditorium, or other enclosure requiring acoustictreatment.

While the latter arrangement overcomes,to a i large extent, theobjections noted above, it still involves certain Operations, such asthe individual assembly and subsequent mounting of the units, whichrequire considerable handling of the parts, and the primary object of mypresent invention is to greatly simpliy the assembly and installation ofacoustic absorbers or sinks of the type set forth above whereby tomaterially reduce the cost of the complete installation.

More particularly, it is an object of my present invention to provide animproved acoustic absorber unit and. an improved acoustic absorbersystem which may be formed therefrom in a facile manner and with a.minimum of Operations.

Another object of my present invention 'is to provide an improved methodof assemblng and installing acoustic absorbers of the type set `forthwhereby both the assembly and the installation or mounting of the unitswill be accomplished in a single operation.

Still another object ofmy present invention is to provide an improvedacoustic absorber of the diffraction type which is neat in appearanceand which may be rendered suitably deoorative.

A further object of my present invention isto provide an improvedmounting arrangement'for acoustic abs'orbers of the type set `forth asaresult of which the individual units can be' rea'dily cleaned Whennecessary.

Still a further' object of my present invention is to provide animproved acoustic *absorber con,-`

which can be reaclily installed even by one un skilled in' the art,which is very' inexpensivein cost, and which 'is highly efcient in use.

As proposed heretofore, the absorber units cr sinks are fabrioated intwohollo-W parte of suitable shape, such as co nes, pyramids,hemispheres, or the like, the -two parts being substantially identicalin shape so that they can be nested'together for compact packlngwhen'assembled for storage or shipment. In accordance with my presentinvention, I provide each part with 'a pe- .ripheral ange so that whenthese partsare butted together with the fianges in *engagement with eachother, the parts form a casing which encloses 'a cavity. The flanges areformed a-tthe large, open-ended, base portions of' the casing -halves,and `I provide a small opening in'the :cena r ter at the opposite orvertex endof each casng` half so that it can be threaded onto tasupporting line, suchas a-wre, string, tape, 'or the like which can bestretched across a room.

To assemble'the unitsor sinks,'the correct number of complemental casinghalves are threaded onto the wire or other suitable line constitutingthe supporting memben'the letter being anchored at one end at a suitablemounting point. After the appropriatenumber of sink halves or artsare'threaded 'onto the wire so that they can be pushed together to formthe clesired'number of complete c'asings or enclosures, the other end ofthe wire or the like is fastened at &suitable point followingapplication of suicient tension thereto to keep it from sagging.Starting at one end of the supporting line, a clamp is placed thereon ata desired location for the first sink. Onehalf of this sink is pushedagainst the clarnp and the second half, with is peripheral fiange acingthe fiange of the first mentioned half, is moved along the supportinglin until the two fianges butt together, after which a second clamp isfastened to the line to hold the two halves together.

The sink or casing halves are constructed of a material which ispervious to sound waves, but which oers a high impedance thereto, astaught by Olson in his above identified application. One material whichhas been found especially suitable is a felted product made from wooclpulp fibers which are accreted by suction from a pulp solution in knownmanner. This material, like blotting paper and the like, is constitutedby a plurality of intertwined fibers of various lengths arranged more orless compactly and indiscriminately in random directions to provide aplurality of irregular, random passages of very small cross-sectionaldimensions. These fine passages acrd communication between the exteriorof the sink casing and the space or cavity enclosed thereby, and theyprovide the requisite dissipative impedance to the acoustical energyreceived thereby. A material of this sort is usually sufficientlyfiexible and yieldable to have enough give to take care of any expansionor contraction of the wire or other similar supporting line due totemperature and humiclity changes. Thus, adequate pressure will alwaysbe maintained between the two casing halves to avoid leaking of the airbetween the cavity enclosed by the casing and the external atmosphere.This method of assembling and mounting the acoustic sinks not onlyavoids separate assembly and mounting Operations, but entirely does awaywith the need for gluing the two casing halves of the sink together.Moreover, the sinks are mounted symmetrically with respect to thesupporting line, and this results in a neat appearance. If, after aperiod of time, the sinks have collected dust on the upper surfacesthereof, they can be rotated easily on the wire to provide ready accessto the dust so that the dust can be brushed off. If desired, the sinkscan be made in various colors and used for decorative purposes.

The novcl features that I consider characteristic of my invention areset forth with particularity in the appended claims. The inventionitself, however, both as to its organization and method of operation, aswell as additional objects and advantages thereof, will best beunderstood from the following description of several embodimentsthereof, when read in connection with the accompanying drawing in whichFigure 1 is a fragmentary, partly sectional view of an enclosurerepresenting a room or the like in which one arrangement of acousticsinks according to my present invention is shown,

Figure 2 is an enlarged, central, longitudinal section of one form ofacoustic absorber or sink according to my present invention,

Figure 3 is a similar view of a slightly different form of absorberaccording to my present invention,

Figure 4 is an end elevation of the supporting line and one form ofclamping member mounted thereon, and

Figure 5 is a View similar to Fig. 1, but showing a somewhat dierentmounting arrangement of 4 acoustic sinks in accordance with my present1nvention.

Referring more particularly to the drawing. wherein similar referencecharacters indicate corresponding parts throughout, and especially toFigs. 2 and 3, there is shown an elongated, flexible, supporting line I,such as a wire, string, tape, or the like, on which is mounted anacoustic absorber 3 comprised of two casing halves 3a and 3b ofsubstantially similar form and symmetrically arranged on the line l.These casin halves are hollow, geometric figures of suitable shape, andmay be cylindrical, conical, pyramidal, hemispherical, or of any othersuitable configuration. A suitable material for the casing halves may bemade by accretion of pulp fibers on a suitably shaped forming screen inthe manner disclosed, for example, in Pare Patent No. 2,488,555, grantedNovember 22, 1949, to provide a layer of intertwined fibers having finepassages therebetween. In the form of the invention shown in Fig. 2, theabsorber unit 3 is made up of two conical casing halves 3a and 3b,whereas in the form shown in Fig 3, the two parts aa and 3b are formedsubstantially as hemispheres. In any case, the casing halves 3a and 3bare open at their larger ends or base portions and are there formed withradially outwardly extcnding peripheral flanges 5a and 5b, respectively.At their opposlte or vertex ends, th casing halves sa and 3b are formedwith small collars Ta and "lb, respectively, (exaggerated somewhat as tosize in the drawing for the purpose of illustration), the collars 'laand 'lb being formed with small openings Sa and 9b of a size justsufiicient to freely receive the supporting line or wire I. Thus, thewire l may be threaded substantially axially through the casing parts 3aand 3b by merely passing the wire through the openings ea and sb andsliding the parts along the wire to any desired location.

In installing an assembly of acoustic absorbers or sinks according to mypresent invention, one end of the wire or line I may first be Secured toone wall of a room ll requiring acoustic treatment, as by means of a,suitable anchoring bolt I 3. The requisite number of casing halves Saand 3b in complemental relation, that is, with the fianges Sa and 5b ofeach cooperating pair facing each other, are then threaded onto the wirel. Finally, the right-hand end of the wire I may be secured to a secondbolt or the like I'I which is Secured to the opposite wall of the roomll, with suitable tension applied to the wire, as by a turnbuckle or thelike (not shown) which may be hidden from view by an appropriate casingor cover of ornamental appearance.

At a suitable location, such as the point I in Fig. l, a suitableanchoring or locking device l5 is placed on the wire. The anchoringdevice !5 may be constituted by a substantially U-shaped, resilientmember provided with oppositely directed slits |5a and I5b to formresilient barbs or the like |5c adapted to bite into the wire l, thespace between the tabs l5c being somewhat smaller than the diameter ofthe wire i. Reading from left to right in Fig. 1, the lefthand anchoringmember [5 is first applied to the wire i sonewhat to the left of itsshown position and it is then moved slightly to the right along the wireI. This causes the barbs l5c thereof to protrude to the left, as clearlyshown in Figs. 2 and 3, so that if an attempt is thereafter made to movethe anchoring member |5 back to the left, the barbs or tabs l5c willbite manner.

into the 'wire and prevent such movement. The casing half sa is thenmoved to the left until its collar 'Iais brought into engagement Withthe left-hand anchoring member [5. Thereafter, the casing part db ismoved over to the left until its fiange b abuts against the flange 5a ofthe casing part sa. The right-hand anchoring member !5 is then appliedto the wire I somewhat to the right of its shown position and it ismoved to the left until it engages the collar lb of the casing half 3band suitable pressure is applied atthe fianges 5a and 5b. The absorberunit at iocation I is then complete. This procedure may be followed foreach of the absorber units or sinks at locations II, III and IV whichrepresent suitable, spaced mounting points along the wire l.

In the form of the invention shown in Fig. 5, the absorber units 3 aremounted on vertically extending lines i which. may be Suspended from theceiling of the room H in any appropriate The lines i may be maintainedunder suitable tension by means of weights' IS which are secure'd `tothe lower ends thereoi. Otherwise, the individual absorber units 3 andthe manner of mounting the same may be similar to that described abovein connection with the horizontal line arrangement of Fig. 1. In anycase, it will be observed that the casing halves :ia and 3?) areassembled and mounted in a single operation and without the necessity ofgluing or otherwise securing the same to each other.

When assembled in the complemental relation shown in the drawing, thecasing parts Sa and se enclose a cavity 20 which is sufficiently largeto have a large acoustic capacitance and thereio'e to provide only avery small acoustic impedance to the incident sound waves received bytheabsorber units 3. The material of which the casing parts aa and 31) aremade is pervious to the sound waves but offers a large, dissipativeimpedance thereto in accordance with the teachings of Olsen in his aboveidentified copending application. Being rather loosely mounted on thesupporting line i so as to be normally freely slidable thereon, it isapparent that the units 3 can be readily rotated on the line despite thefact that they are anchored against longitudinal movementthereon Thus,when dust has' accumulated on. the top surfaces thereof, they can beeasily rotated through a sufiicient angle to permit ready access to theportions requiring cleaning. Also, it will undoubtedly be apparent thatthe unit's or sinks 3 can be made suitably decorative to enhance theappearance of the room in addition to providingthe desired acousticefleote. All these and other advantages are affordecl by the presentinvention while still permitting the individual casing halves to beassembled in nested relation for storage and the like.

Although I have' shown and described several I arrangemcnts and types ofacoustic absorbers according to my present invention, it will, no doubt,be apparent to those skilled in the art that many other variations arepossible. .For example, the oasing halves 3a and 3b need not be made asgeometric figures having surfaces of revolution, but may be in the formof pyramids, parallelepipeds, or the like', and if they are formed onsurfaces of revolution, they may be ellipsoids, tori, or the like.Furthermore, where it is not found desirable to make the sinks 3 ofyielding material, the looking members l5 may be provided with ayieldable spring element which will have the requisite givelongitudinallyalong 'the' line l. Also, instead of the type' of clampingor anchoring member l shown in detail inFig. i, other `suitable forms ofanchoring members may be employed, such as an ordinary slidable collarwith a looking set screw. If the latter form of looking member is used,then it will obviously be necessary to firstthread one locking collaronto the line I followed by two complemental casing halves sa and 31),in turn followed by a second looking collar. Of course, the latter formof looking member may be C-shaped or U-shaped, in which case theassembly may be made as described above in connection with Fig. 1. Othervariations will undoubtedly readily suggest themselves to those skilledin the art. 'I thereore desire that myinvention shall not be limitedexcept insoiar as is made necessary by the prior art and by the spiritof the appended' claims.

I claim as my invention:

1. A diffraction type acoustic absorbing system comprising an elongatedsupporting member and a plurality of acoustic absorbing devices mountedon said member at spaced points therealong, said devices each comprisinga pair of complemental, hollow parts formed of sound absorbing materialand cooperatively arranged to enclose a cavity, and said member passingsubstantially axially through said parts.

2. A diffraction type acoustic absorbing system comprising an elongatedsupporting member and a plurality of 'acoustic absorbing devices mountedon said member at spaced points therealong, said devices each comprising a pair of complemental, hollow parts :formed of sound absorbngmaterial and cooperatively arranged to enclose a cavity, the partsofeach pair being substantially similar in configuration, and said memberpassing subi stantially axially through said parts.

3. A diffraction type acoustic absorbing system comprising an elongatedsupporting member adapted ,to be Suspended in space, a plurality ofdevices formed of sound absorbing material mounted on said 'member atspaced points therealong, said devices each comprising a hollowstructure enclosing a cavity and being normally freely slidable on saidmember, and means anchoring said devices to said member at 'said points.

4. A diraction type acoustic absorbing system comprising an elongatedsupporting membena plurality of devices formed of sound absorbingmaterial mounted on said member at spaced points therealong, saiddevices each comprising a pair of complemental, hollow partscooperatively arranged to enclose a cavity and being normally freelyslidable on said member, said member :passing substantially axiallytherethrough, and means anchoring said devices to said member at saidpoints.

5. An acoustic absorbing system according to' claim 4 characterized inthat said material is provided with a plurality of five passagestherethrough whereby it is pervious to acoustical waves, said passageshaving such fine dimensions as to offer a large dissipative impedance tosaid Waves,

'7. An acoustical absorbing system according to claim 4 characterized inthat each of said parts is constituted by a casing portion open at oneend, characterized further in that said devices are each so arranged onsaid member that the open ends of the parts thereof are in abuttingrelation whereby to enclose a cavity, and characterized still further inthat said anchoring means maintains each cooperative pair of said partsin cavity enclosing relation on said member.

8. An acoustical absorbing system according to claim 4 characterized inthat each of said parts is constituted by a casing portion open at oneend, characterized further in that said devices are each so arranged onsaid member that the open ends of the parts thereof are in abuttingrelation whereby to enclose a cavity, and characterized still further inthat said anchoring means maintains each cooperative pair of said partson said member in cavity enclosing relation and in pressing engagementwith each other.

9. An acoustical absorbing system according to claim 4 characterized inthat each of said parts is constituted by a casing portion open at oneend and terminatin in a fiange, characterized further in that saiddevices are each so arranged on said member that said open ends of theparts thereof are in substantially aligned relation and the flanges ofthe parts thereof are in abutting reiation whereby to enclose a cavity,and characterized still further in that said anchoring means maintanseach cooperative pair of said parts in cavity enclosing relation on saidmember.

10. An acoustical absorbing system according to claim characterized inthat each of said parts is constituted by a casing portion having alarge opening at one end and a small opening at the opposte end, saidsmall openings being of a size just sufiicient to freely receive saidsupporting member, characteriaed further in that said de- Vices are eachso arranged on said member that said first named ends of the partsthereof are in abutting relation whereby said large openings are inaligned relation and said parts enclose a cavity, characterized furtherin that said member passes through said small openings and said. cavity,and characterized still further in that said anchoring means maintainseach cooperative pair of said parte in cavity enclosing relation.

11. An acoustical absorbing system according to claim 4 characterized inthat each of said parts is constituted by a tapered casing portion openat its large end and having a small opening at its smaller end of a sizejust sufficient to freely receive said supporting member, charaeterizedi further in that said devices are so arranged on said member that thelarge ends of the parts thereof are in abutting relation whereby saidparts enclose a cavity, characterized further in that said member passesthrough said small openings and said cavity, and characterized stillfurther in that said anchoring means is secured to said member inabutting relation to said smaller ends and maintains each cooperativepair of said parts in cavity enclosing relation.

12. A diffraction type acoustic absorber comprisng a pair ofcomplemental, hollow parts each having an open end and an opposed,closed end, said open end terminating in a. fiange and said closed endhaving a small opening therein for the receptcn of a supporting member,said parts being adapted to be assembled in a relation wherein saidfianges will face and abut each other and said open ends Will be insubstantial alignment with each other whereby said parts will provide acasing which encloses a cavity, said openings being then at opposed endsof said casing, and said parts being constituted by a material which isprovided with a plurality of passages therethrough whereby it ispervious to acoustical Waves, said passages having such fine dimensionsas to offer a relatively large dlssipative impedance to acousticalenergy received thereby.

13. A difiraction type acoustic absorber according to claim 12characterized in that said parts are each constituted by a. geometricbody having a surface of revolution.

14. A diffraction type acoustic absorber according to claim 12characterized in that said parts are each consttuted by a. tapered,geometric body having a base end and an apex end, characterized furtherin that said fiange extends outwardly from said body at said base end,and characterized still further in that said small opening is providedat said apex end.

GEORGE L. BEERS.

REFERENCES CITED The following references are of record in the fle ofthis patent:

UNITED STATES PATENTS Number Name Date 271,'749 Stewart Feb. 6, 18831,483,365 Mazer Feb. 12, 1924 1308354 King June 2, 1931 1,816,618 SklarJuly 28, 1931 2,1G0,638 Bedell et al. May 30, 1939 2,238,167 Genest Apr.15, 1941 FOREIGN PATENTS Number Country Date 102914 Australia Jan. 6,1938 certificate of correction Patent No. 2,502,017 March 28, 1950GEORGE L. BEERS It is hereby Certified that errors appear in the printedspecificaton of the above numbered patent requirng correction asfollows:

Column 3, line 6, for the Words "with is read 'with its; column 6, line64, for "five" read fine;

and that the said Letters Petent should be read With these correctionstherein that the same may conform to the record of the case in thePatent Ofice.

Signed and sealed this 25th day of July, A. D. 1950 [SEAL] THOMAS F.MURPHY,

Assistant C'omm'ssioner of Patents.

certificate of correction r Patent No. 2,502,017 March 28, 1950 GEORGEL. BEERS It is hereby Certified that errors appear in the prntedspecifioaton of the above numbered patent requiring correction asfollows:

Column 3, line 6, for the words With is read with its; column 6, line64, for "five" read fine;

and that the said Letters Patent should be read with these correctionstheren that the same may conform to the record of the case in the PatentOffice.

Signed and sealed this 25th day of July, A. D. 1950 [SEAL] THOMAS F.MURPHY,

Assistant 'ommssioner of Patents.

certificate of Correction I Patent No. 2,502,017 March 28, 1950 GEORGEL. BEERS It is hereby certified that errors appear in the printedspeeificaton of the above numbered patent requirng correction asfollows:

Column 3, line 6, for the Words "With is read with its; column 6, line64, for "five read fine;

and that the said Letters Patent should be read With these correctionstherein that the same may conform to the record of the case in thePatent Ofice.

Signed and sealed this 25th day of July, A. D. 1950 THOMAS F. MURPHY,

Assistant 'omm'ssioner of Patents.

